An electronic apparatus including a button battery as its power source is sometimes used in a state where a battery holder that holds the button battery is detachably mounted on the electronic apparatus (for example, Patent Literatures 1 and 2). The button battery is mounted on the electronic apparatus in a state where the button battery is held in the battery holder, so that the button battery does not drop out of the electronic apparatus during the mounting. However, if the battery holder drops when the battery holder is attached or detached from the electronic apparatus, the button battery can come off the battery holder on the impact and can become lost.
Patent Literature 3 discloses a battery holder having a pair of slits in its side wall. The side wall serves as a flexible portion, and a projection for holding a battery is formed on the inner surface of the flexible portion. The battery is stored into a storage chamber of the battery holder while expanding the flexible portion outward. The battery stored in the storage chamber is held by the projection formed on the inner surface of the flexible portion. Thus, the battery is prevented from dropping off.
Patent Literature 4 discloses a battery holder having a latch on the inside of its side wall. The latch elastically shifts outward or inward together with the side wall, and a locking claw for holding a battery is formed at the upper end of the latch. The battery is stored into a storage chamber of the battery holder while expanding the upper end of the latch outward. The battery stored in the storage chamber is held by the latch and the locking claw that is formed at the upper end of the latch. Thus, the battery is prevented from dropping off.